1. Field of the Invention
The present invention relates generally to device capable of projecting a light beam which assists in the aiming of a firearm. More particularly, the invention relates to such a light beam target designator having a pair of light sources and capable of selectively projecting either light sources through a common focusing and deflecting assembly.
For some time, light beams have been used to assist in the aiming of firearms. Commercially available devices commonly employ lasers as a light source and are mounted on the firearm so that the laser beam is precisely aligned with the bore or shaft of the weapon. Frequently, the laser is mounted within an enclosure, and the enclosure is adjustably attached to the firearm so that the alignment of the laser beam relative to the bore or shaft of the firearm may be adjusted to compensate for factors such as distance to the target, windage, and the like.
Usually, such laser target designators employ a visible light beam for use during daylight hours. The use of visible light beams at night, however, is disadvantageous since it is often possible to trace a visible light beam back to its source. This is undesirable during military operations since it would allow the opposing forces to quickly identify the point of origin of the fire. For this reason, laser target designators employing infrared beams have been developed. Such infrared beams are visible to those using infrared image intensifers, but invisible to all others. Such infrared target disignators may thus be used with relative safety at night.
Heretofore, to obtain both night and day operation capability, it has been necessary for troops and others to have available both visible light and infrared target disignators. The use of such separate systems, however, is undesirable for several reasons. First, the amount of equipment which must be carried by the troops is doubled. Second, the target designator must be changed at both dawn and nightfall when troops are on alert. Finally, in some situations the troops will be rapidly moving between light and dark conditions where the changing of the designator is effectively impossible.
For these reasons, it would be desirable to provide a single target designator device capable of selectively projecting either visible light or infrared light target designating beams. Moreover, it would be desirable if such a device could employ a common focusing and deflecting means for both beams so that when the beam sources change, the new designating beam is directed along exactly the same path as the old designating beam.
2. Description of the Relevant Art
U.S. Pat. Nos. 4,291,478; 4,161,076; and 4,212,109 each disclose laser target designators employing a single light source. U.S. Pat. Nos. 3,918,813; 4,260,254; and 4,266,873 each disclose laser alignment systems which allow a user to view the laser beam through the laser focusing system. U.S. Pat. No. 4,385,834 discloses a wedge system for aligning a beam deflecting prism. Also of relevance to the present invention are U.S. Pat. Nos. 2,653,386; 3,752,587; 3,803,399; 4,313,272; 4,313,273; 4,317,304; and 4,349,838.